I'm doing research for a 2021 trip to Northern Europe. On the Copenhagen Card website I encountered this statement: "Unfortunately it is not possible to buy Copenhagen Cards from June 27 - August 6, as several museums and attractions offer 50% discount of the entry price during this period. We refer to the specific attraction's website for ticket information."
So anyone (Canadians? UK residents? expats living in Europe?) planning to visit Copenhagen in July or early August may get some bargains. Travelers with trips spanning August 6 should research their target sights to figure out which ones are best visited early, before the entry fees go back up.
I've been wondering whether there would be any reductions offered during the early post-lockdown period, but this is the first evidence I've seen that it may happen. However, I haven't spent much time on sightseeing websites yet.